1. Field of the Invention
The present invention relates to polynucleotides having leader sequence function. In particular the invention relates to polynucleotides having leader sequence function in fungal host cells. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing polypeptides using the polynucleotides of the invention.
2. Background of the Invention
The recombinant production of a heterologous protein in a fungal host cell, particularly a filamentous fungal cell such as Aspergillus, may provide for a more desirable vehicle for producing the protein in commercially relevant quantities.
Recombinant production of a heterologous protein is generally accomplished by constructing an expression cassette in which the DNA coding for the protein is placed under the expression control of a promoter, excised from a regulated gene, suitable for the host cell. The expression cassette is introduced into the host cell. Production of the heterologous protein is then achieved by culturing the transformed host cell under inducing conditions necessary for the proper functioning of the promoter contained on the expression cassette.
Improvement of the recombinant production of proteins generally requires the availability of new regulatory sequences which are suitable for controlling the expression of the proteins in a host cell. The regulatory sequence could be a suitable leader sequence, which is a nontranslated region of an mRNA that is important for translation by the host cell. The leader sequence is operably linked to the 5′ terminus of the nucleotide sequence encoding the polypeptide.
Well knwon leaders for filamentous fungal host cells have previously been obtained from e.g. the genes for Aspergillus oryzae TAKA amylase and Aspergillus nidulans triose phosphate isomerase.
It is an object of the present invention to provide new leader sequences for use in fungal host cells and further provide improved methods for producing a polypeptide in a fungal host cell using the new leader sequences.